Magnetoresistivity Dynamics in Microfine Graphite under Pressure

The basal plane resistivity of packed pyrolytic graphite was measured as a function of temperature, high hydrostatic pressure up to 1,6 GPa and magnetic fields up to 1 T. Our graphite sample shows a transition from negative magnetoresistivity at some low temperatures to positive one with the temperature growing. Resistivity behaviur suggests for ordering transition about 0,5 GPa. Pressure over the ordering transition suppresses magnetoresistivity of both signs and shifts zero magnetoresistivity point to the lowest temperatures. All of the effects are of elastic character – no change with high accuracy in the resistivity dependencies after unloading to normal pressure can be detected. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3537

Duality in Quantum Liouville Theory

The quantisation of the two-dimensional Liouville field theory is investigated using the path integral, on the sphere, in the large radius limit. The general form of the $N$-point functions of vertex operators is found and the three-point function is derived explicitly. In previous work it was inferred that the three-point function should possess a two-dimensional lattice of poles in the parameter space (as opposed to a one-dimensional lattice one would expect from the standard Liouville potential). Here we argue that the two-dimensionality of the lattice has its origin in the duality of the quantum mechanical Liouville states and we incorporate this duality into the path integral by using a two-exponential potential. Contrary to what one might expect, this does not violate conformal invariance; and has the great advantage of producing the two-dimensional lattice in a natural way.Comment: Plain TeX File; 36 page

Prediction of Wearing out of Power Transformer Winding Insulation

Importance of the different parameters of wearing out of power transformer insulation prediction structure, operating factors, selection of configuration and parameters of paper insulation and transformer oil technical state models is investigated. Prediction of wearing out of power transformer winding insulation is reduced to the stochastic prediction of load dynamics and ambient temperature, simulation of the changes of technical states of paper insulation and transformer oil, aging calculations and probabilistic estimation of insulation wearing out. Computer simulation of power transformer insulation wearing out for the next ten years of operation is performed.Исследована значимость различных параметров структуры прогноза износа изоляции силового трансформатора, факторов эксплуатации, произведен выбор структуры и параметров моделей технического состояния бумажной изоляции и трансформаторного масла. Прогнозирование износа изоляции обмоток силового маслонаполненного трансформатора сведено к стохастическому прогнозированию динамики нагрузки, температуры окружающей среды, имитационному моделированию изменений технического состояния бумажной изоляции и трансформаторного масла, расчету старения и вероятностной оценке величины износа изоляции. Выполнено компьютерное моделирование износа изоляции силового трансформатора в течение предстоящих десяти лет эксплуатации

Влияние концентрации регуляторов роста в культуре цветоложа капусты брокколи (Brassica oleraceа var. italica)

The results of the cultivation of different explants of broccoli in vitro in the presence of different growth regulators. The influence of the concentration of growth regulators on the morphogenesis of broccoli transplants. The optimal age and type of bud explants. Fully described the whole process of obtaining plants regenerated in vitro, including their adaptation to the open ground. A number of new technological solutions in the method of micropropagation of this culture.В статье приведены результаты культивирования эксплантов капусты брокколи in vitro в присутствии различных регуляторов роста. Установлено влияние концентраций регуляторов роста на морфогенез трансплантов капусты брокколи. Выявлены оптимальный возраст бутона и тип экспланта. Полностью описан весь технологический процесс получения растений-регенерантов in vitrо, включая их адаптацию к условиям открытого грунта. Представлен ряд новых технологических решений в методе микроклонального размножения данной культуры

Constrained Analysis of Topologically Massive Gravity

We quantize the Einstein gravity in the formalism of weak gravitational fields by using the constrained Hamiltonian method. Special emphasis is given to the 2+1 spacetime dimensional case where a (topological) Chern-Simons term is added to the Lagrangian.Comment: 15 pages, IF-UFRJ-21/9

Effective Theoretical Approach to Back Reaction of the Dynamical Casimir Effect in 1+1 Dimensions

We present an approach to studying the Casimir effects by means of the effective theory. An essential point of our approach is replacing the mirror separation into the size of space S^1 in the adiabatic approximation. It is natural to identify the size of space S^1 with the scale factor of the Robertson-Walker-type metric. This replacement simplifies the construction of a class of effective models to study the Casimir effects. To check the validity of this replacement we construct a model for a scalar field coupling to the two-dimensional gravity and calculate the Casimir effects by the effective action for the variable scale factor. Our effective action consists of the classical kinetic term of the mirror separation and the quantum correction derived by the path-integral method. The quantum correction naturally contains both the Casimir energy term and the back-reaction term of the dynamical Casimir effect, the latter of which is expressed by the conformal anomaly. The resultant effective action describes the dynamical vacuum pressure, i.e., the dynamical Casimir force. We confirm that the force depends on the relative velocity of the mirrors, and that it is always attractive and stronger than the static Casimir force within the adiabatic approximation.Comment: Published Version, 16 pages, LaTeX2e with graphics package, 1 figur

Path Integral Formulation of the Conformal Wess-Zumino-Witten to Toda Reductions

The phase space path integral Wess-Zumino-Witten $\to$ Toda reductions are formulated in a manifestly conformally invariant way. For this purpose, the method of Batalin, Fradkin, and Vilkovisky, adapted to conformal field theories, with chiral constraints, on compact two dimensional Riemannian manifolds, is used. It is shown that the zero modes of the Lagrange multipliers produce the Toda potential and the gradients produce the WZW anomaly. This anomaly is crucial for proving the Fradkin-Vilkovisky theorem concerning gauge invariance.Comment: Plain TeX file, 27 page

Classical Open String Models in 4-Dim Minkowski Spacetime

Classical bosonic open string models in fourdimensional Minkowski spacetime are discussed. A special attention is paid to the choice of edge conditions, which can follow consistently from the action principle. We consider lagrangians that can depend on second order derivatives of worldsheet coordinates. A revised interpretation of the variational problem for such theories is given. We derive a general form of a boundary term that can be added to the open string action to control edge conditions and modify conservation laws. An extended boundary problem for minimal surfaces is examined. Following the treatment of this model in the geometric approach, we obtain that classical open string states correspond to solutions of a complex Liouville equation. In contrast to the Nambu-Goto case, the Liouville potential is finite and constant at worldsheet boundaries. The phase part of the potential defines topological sectors of solutions.Comment: 25 pages, LaTeX, preprint TPJU-28-93 (the previous version was truncated by ftp...

ОСОБЕННОСТИ ФОРМИРОВАНИЯ ФУНКЦИОНАЛЬНОЙ МЕЖПОЛУШАРНОЙ АСИММЕТРИИ У ДЕТЕЙ И ПОДРОСТКОВ С ЭССЕНЦИАЛЬНОЙ АРТЕРИАЛЬНОЙ ГИПЕРТЕНЗИЕЙ

Objective: Peculiarities and age dynamics of hemispheric asymmetry investigation in children and adolescents with hypertension. Methods: 196 children and adolescents aged 10 to 17 years (15.0±1.4), including 98 patients with arterial hypertension (AH) (15.1±1.5) and 98 healthy children of the control group (14.9±1.3). The number of boys in the comparison group and the main group of patients with AH was 60 (61.2%) and 59 (60.2%), girls — 37 (37.8%) and 39 (39.8%), respectively. Results: The majority of children and adolescents with hypertension sensorimotor asymmetry differed by low intensity, indicating a decline in the dominance of the left hemisphere. Accumulation of ambi- and left lateral features traced mainly in motor (53.6%) and auditory (60.2%) system, while asymmetry in the visual analyzer did not differ from the control group. Differences in the degree of hemispheric asymmetry increases in the ontogeny compared to control group. Conclusion: Identification of specificity hemispheric interaction in patients with hypertension (low asymmetry and its weak performance in ontogeny) can be considered not only as a pathological consequence of hypertension, but also as a compensatory mechanism for the redistribution of loads to the right hemisphere in terms of the functional deficit of the left hemisphere. It can be assumed that the rear parts of the brain may play a significant role in the processes of adaptation and compensation of occurring disorders in hypertension. Цель исследования: исследовать возрастную динамику и особенности межполушарной асимметрии у детей и подростков с эссенциальной артериальной гипертензией. Методы: проведено обследование 196 детей и подростков в возрасте от 10 до 17 лет, в т.ч. 98 пациентов с эссенциальной артериальной гипертензией (ЭАГ) (средний возраст 15,1±1,5 года) и 98 здоровых детей группы сравнения (средний возраст 14,9±1,3 года). Число мальчиков в группе сравнения и в основной группе пациентов с ЭАГ составило 60 (61,2%) и 59 (60,2%), девочек — 37 (37,8%) и 39 (39,8%), соответственно. Результаты: у 82,7% детей и подростков с ЭАГ сенсомоторная асимметрия отличалась низкой степенью выраженности по сравнению с группой сравнения, что указывало на снижение доминирования (по исследуемым характеристикам) левого полушария. Накопление амби- и леволатеральных черт пациентов с ЭАГ прослеживалось преимущественно в моторной (53,6%) и слуховой (60,2%) системе, в то время как асимметрия в зрительном анализаторе не отличалась от показателей группы сравнения. В процессе онтогенеза расхождение в степени выраженности межполушарной асимметрии по сравнению с контролем нарастало: если в младшей возрастной группе такие изменения только намечались (p 0,1), то в старших группах они приобретали отчетливый характер (p 0,001). Выводы: выявленная специфика межполушарного взаимодействия у больных с ЭАГ (низкий уровень асимметрии и слабая динамика в онтогенезе) может свидетельствовать не только о патологическом влиянии артериальной гипертензии, но и о компенсаторном механизме перераспределения нагрузок на правое полушарие в условиях функционального дефицита левого полушария. Можно предположить, что задние отделы мозга играют важную роль в процессах адаптации и компенсации нарушений, возникающих при ЭАГ.

Curved QCD string dynamics

We consider the effects of going beyond the approximation of a straight string in mesons by using a flexible flux tube model wherein a Nambu-Goto string bends in response to quark accelerations. The curved string is dynamically identical to the straight string even for ultra-relativistic mesons except for a small additional radial momentum. We numerically solve the curved string model in the case where both ends have equal mass quarks and also the case where one end is fixed. No approximation of non-relativistic motion is made. We note some small but interesting difference from the straight string.Comment: 12 pages REVTeX, 10 PostScript Figure